1. Field of the Invention
The present invention relates to battery wristwatches, and more particularly, to wristwatches having switches that are externally operated.
2. Prior Art
In the past years, light emitting diodes and liquid crystal display elements have become widely employed for time display devices in timepieces. Since these devices have their electronic circuits compactly integrated, they have expandable applications depending upon demand by adding an accesory, such as a memory circuit or a calculator circuit. However, the more the display device has, the more switch means are required to perform these functions. As a result, using a conventional type of switch means, such as push buttons or rotatable crowns it is difficult to maintain satisfactory waterproofing between the watch case and the switch devices. In order to achieve good waterproofing, a more complex process is required to manufacture those watches which would lead to a high manufacturing cost.
Particularly in the case of light emitting diodes and liquid crystal display elements, whose durability might be easily damaged by humidity, the protection against humidity is a big requirement. Another consideration which is peculiar to watches is that they are designed so tightly that once humidified inside, the watch cannot be free from humidity for a long time. Therefore, humidity must be strictly shut off at the switch means-watchcase contact.
In an attempt to satisfy this requirement, it has been commercially introduced to utilize a "reed switch", i.e. magnetic-sensitive elements, whose leads comprise two or three thin tips confronting each other and which are capsulated altogether. This switch functions as a switch means when it is placed in a circumstance magnetic field to a certain degree. Accordingly, the conventional push buttons or rotatable crowns may be substituted for by a reed switch which works upon bringing a magnet close to the watchcase containing the reed switch as its integral part, thereby improving the waterproof competency.
Most of the prior art watches using those reed switches, however, have their whole switch mechanism made of a combination of reed switches and push buttons where reed switches are used only for adjusting the time and the rest of the switching operation is to be done by push buttons. In these watches, the waterproof competency cannot be satisfactorily high in spite of the reed switches. Furthermore, since the magnet is operated separately from the watch case, it often causes inconveniences such as losing the magnet, taking longer time in the operation. In addition, the number of those reed switches is practically limited to utmost three, for the magnet would affect any neighboring switches besides the particular switch which the user wants to operate, if they are planted too close to each other.